U.K. Patent No. 827172 (1960) teaches that a mixture (hard butter) obtained by mixing a palm mid-fraction, and Borneo tallow or a Borneo tallow type fat such as Shorea robusta, etc. in a ratio of 25:75 to 75:25 is good for a cocoa butter substitute. According to the specification of this U.K. Patent, Borneo tallow or the Borneo tallow type fat used contains not less than 50%, preferably, not less than 60% of triglycerides composed of one unsaturated fatty acid residue (U) substantially derived from oleic acid (O) and two saturated fatty acid residues (S) rich in those derived from palmitic acid (P) and stearic acid (St). Almost all the remaining triglycerides are those composed of two unsaturated fatty acid residues (U) and one saturated fatty acid residue (S). Further, according to the specification, it is desirable to minimize the amount of triglycerides composed of three saturated fatty acid residues (SSS) and/or three unsaturated fatty acid residues (UUU).
An analogous technique is disclosed in Japanese Patent Laid Open Publication No. 115863/1978. This publication teaches a hard butter containing triglycerides composed of saturated fatty acid residues substantially derived from fatty acids selected from P, St and arachic acid and unsaturated fatty acid residues substantially derived from fatty acids selected from O and linoleic acid, wherein the amount of the residue derived from arachidic acid is 4 to 15% based on total of S, and the amount of the residue derived from linoleic acid is not more than 20% based on total of U. The constituent triglycerides of this hard butter contain 50 to 80%, preferably, 55 to 75% of SUS (.beta.-unsaturated- .alpha.,.alpha.'-disaturated triglyceride); 15 to 50%, preferably, 25 to 45% of SUU ( .alpha.or .alpha.'-saturated diunsaturated triglyceride); 1 to 5 , preferably, 1 to 3% of SSS: not more than 5%, preferably, not more than 3% of USU ( .alpha.or.alpha.'-diunsaturated triglyceride): and not more than 6%, preferably, not more than 4% of UUU.
The constituent triglycerides of Shorea robusta disclosed in the above U.K. Patent Specification contain a relatively large amount of arachic acid residue in addition to the residues derived from P and St. However, they scarcely contain fatty acid residues derived from fatty acids having longer carbon chains. Further, although the amount of arachic acid is defined in the above Japanese Patent Laid Open Publication, it does not teach the effect of fatty acids having longer carbon chains as constituent fatty acids of triglycerides.
On the other hand, Japanese Patent Publication No. 27497/1985 discloses a process for producing a trans-acid type hard butter having a specific fatty acid composition consisting of elaidic acid, palmitic acid, behenic acid and other fatty acids, wherein the fatty acid residues are randomly distributed. However, such a trans-acid type hard butter has inferior miscibility with cocoa butter (i.e., difficulty of uniform crystallization during a tempering step) and, therefore, has drawbacks, for example, poor taste of fatty confectionery such as chocolate produced by using the hard butter due to significant limitation to the amount of coca-liquor.
By the way, recently, preference for food has tended to be for soft food. On the other hand, in this field, it has been requested to develop a hard butter which maintains a certain degree of hardness even at a high temperature, and does not produce or is hard to produce "fat blooming". However, both of these requested properties are quite inconsistent with each other and it is very difficult to impart both properties to a hard butter, simultaneously. In addition, a hard butter to be used as a cocoa butter substitute should have such a property that it should melt rapidly and sharply at about body temperature. Further, workability of tempering thereof is also an important factor. In this regard, even if the difference in compositions of hard butters is only a very little, the above property and factor are significantly varied, and it is very difficult to find a relation between properties and compositions of hard butters even for those skilled in the art. For example, although a fat or oil containing a large amount of diglycerides and/or dihydroxy fatty acid glycerides advantageously effects improvement of antiblooming property, tempering is inhibited because formation of crystal nucleus and crystal growth in a tempering step are slow and, in general, excess cooling is required, which results in inconveniences during working such as slow solidification rate, difficulty in release from a mold in a molding step, etc.
The present inventors have intensively studied to obtain a hard butter which has mouth feel suitable for imparting soft biting property, and also has a certain degree of hardness at a high temperature with good antiblooming property as well as good workability during production such as in a tempering step and, in addition, can rapidly and sharply melt at about body temperature. As the result, it has been found that triglycerides containing saturated fatty acids having carbon chains which are longer than or the same as that of arachic acid as the constituent saturated fatty acids at .alpha. and/or .alpha.' make it possible to obtain a hard butter having both suitable anti-blooming property and good miscibility with cocoa butter without diglycerides or dihydroxy fatty acid glycerides which inhibit tempering, and to produce fatty confectionery such as chocolate having softer mouth feel.